The present invention relates to compositions which provide silicone pressure-sensitive adhesives, herein also denoted as SPSAs. More specifically, the present invention relates to compositions which provide SPSAs which have improved properties subsequent to their removal from a fluorosilicone release liner.
The adhesive aggressiveness of SPSAs is well documented in the silicone art. While aggressive adhesiveness, i.e. tack and/or adhesive strength, of SPSAs has utility it is also a significant problem. Whether the SPSA has the form of, for example, an adhesive layer on a substrate in the form of a roll of tape; an adhesive layer on an article protected with a peelable backing, such as a decorative trim item to be adhered to an automobile or a medical item to be adhered to the skin of a person: or a transfer adhesive layer protected on two surfaces by peelable backings, the SPSA must be separated from an adjacent surface before it can be used for its intended purpose.
Recently, Brown and Stickles, U.S. Pat. No. 4,736,048, disclosed a fluorosilicone release liner which is said to be useful for releasing solvent-cast, heat-cured SPSAs. Patentees provided examples of laminates comprising peroxide-cured SPSAs, which had been solvent-cast and heat-cured in contact with their fluorosilicone liner; however, they did not disclose any examples of a laminate comprising a platinum-cured SPSA.
In copending U.S. patent application Ser. No. 276,178 filed on Nov. 23, 1988 and titled "PRESSURE SENSITIVE ADHESIVE/RELEASE LINER LAMINATE", Tangney disclosed a laminate comprising an addition-curing SPSA and a fluorosilicone release coating. The release force needed to separate the addition-cured SPSA from the fluorosilicone release coating, after it had been cast onto and cured in contact with the release coating, had a stable value of less than 300 grams per inch, while at the same time displaying stable subsequent adhesiveness and stable subsequent tack.
However, while the laminate of the copending application is a highly desirable article it has one shortcoming. It has been noticed that after the SPSA has been separated from its liner its tack, called subsequent tack, and/or its adhesion, called subsequent, are not as high as sometimes desired.